Process for the production of a compound metal



Patented Oct. 5, 192 6.

Y for producing compound metal articles and EMILIO 'ROMANELLI, or BLLAMP COMPANY, A co :enoons's FOR THE PRODUCTION or .& comrouun METAL.

No Drawing. Application filed January 4,

This invention relates to a new process especially leading-1n wires for.incandescent electric lamps. An object of this invention is a processof producing a compound metal. which will have exactly a predeterminedcoeflicient of expansion.

A special obje ct of the invention is a .methodof producing a clad metalhaving no air spaces between the layers of the-metals comprising thecompound. '.Such a compound metal article is valuable for many purposesbut for incandescent lamps. lows the use of 'any'kind of glass for thebulb of the lamp without lead-in wire nite co-eiiicient of particularlyso as a It albeing limited to a defiexpansion, because, by this process,a wire can be produced which will meet allthe requirements of a goodlead-in wire, including a co-eflicient of expansion close enough to thatof the' glass selected to .maintain an air-tight seal between it and theglass throughout to which an incan the range of temperature descent lampis subject.

I Platinum has been displacedas a lead-in wire for incandescent electriclamps by composite metals of which an example is a copper-coated nickelsteel wire. Obviously the contact between the copper and the. nickelsteel core must be close enough to prevent air from passing between themwhen the wire is sealed into a lamp. manufacturing such quently produceit tween the layers at ence of this air gives Present processes of withpockets of air besome parts. The presthe wire a different coefficient ofexpansion where a pocket exists.

Defective wire of lamp, permits air I therefore, causes life.

A good leadin this sort, when used in a to leak into the bulb and, thelamp to have a short -in wire should be free from pockets and have acoeiiicient of expansion substantially equal to that of the glass intowhich it is sealed. With a nickel steel alloy of a given com- 1position, the. coefiicient of expansion of the 'copper-coated-nickelsteel wire depends on the relative thickness of the metals composing it.The coefficient of expansion of such wire may be largely controlled byregulating the amount the core.

of copper deposited upon Other defects of present practice in makacomposite wire fre- 1,601,982 {PATENT OFFICE.

OOMFIELD, NEW JERSEY, ASSIGNOR TO WESTINGHOUSE RPQRATION OFPENNSYLVANIA.

1921, sum in. 435,027. Renewed February 25, 1926.

ing composite wire of the nature described are the great difliculty inregulating the th ckness of the coppercoating and the nonumformthickness of copper around the perimeter of the wire.

The method of practicing my invention by which I have overcome thedefects of prevlous processes, is as follows A. rod of nickel steelabout 400 mil in diameter and 5 ft. long is cleaned in an alkali,followed by a cleaning in an acid to remove metallic oxides and scales.The rod is then electroplated with copper about 1 mil in thickness in apreliminary bath of the following composition:

. Grams. Sodium sulphite (Na SO 20 Sodium carbonate (Na CO -1OH O) 20Sodium bisulphite (NaHSO 20 Gupric acetate (Cu(O H O -11 0) 20 Potassiumcyanide (100%KCN) Water,"1 liter.

The current density used is from three tenths (0.3) to one (-1) ampereper square decimeter. The copper-plated rod is then electroplated" withcopper to the desired thickness in another bath of the followingcomposition Copper sulphate, 480 gms; sulphuric five (5) to'ten (10) am-If desired, a coating of zinc, or other I metal which has a meltingpoint lower than copper and which will alloy with both the nickel steeland the copper, may be put on the core before depositing the copper, inorder to'make the copper coating more adherent. However, it is notnecessary to use a metal between the nickel steel core and the copper.

From the foregoing it will be apparent that my invention provides aquick audaccurate method formanufacturing a composite wire which shallhave exactly the coefiicient of expansion desired, inasmuch as thethickness of the copper plating may be exactly controlled by measuringthe amountof currentpassed through the plating circuit and the timeduring which it is passed, both of which quantities may be accuratelymeasured. This method also results in a uniform thickness of copper overthe whole surface of the wire. I 7

It will be understood that, while I have described the process for theproduction of a copper-clad nickel steel wire, my invention isapplicable to other suitable metals.

What is claimed is:

1. A step in the process of producing a composite metallic body whichconsists in electroplating on a metallic core another metal of suchthickness as to give to the composite body a predetermined coefficientof expansion.

2. The process of producing a composite metallic body which consists inelectroplating on a metallic core another metal of such thickness as togive to the composite body a redetermined coefficient ofexpansion, andheating the deposited metal to incipient fusion.

3. The process of producing a composite metallic body which consists inelectroplating a core of nickel steel With copper and heating the saidcopper to incipient fusion.

4. A method for accurately controlling the coefficient of expansion of acomposite wire which consists in electrolytically depositing on ametallic core a predetermined amount of another metal.

5. The method of producing a composite t-roplating a thin coating ofcopper from a cyanide bath and depositing on the said coating :1 secondcoating from a sulphate bath and thereafter heating said body to causeincipient fusion of the coatings thereon.

.6. As an article of manufacture, a composite wire free from pocketsbetween the layers thereof.

7. As an article of manufacture, a com posite wire composed ofconstituent layers having their adjoining surfaces in intimate contact,whereby pockets between said layers are obviated.

8. As an article of manufacture a composite wire free from pocketsbetween the layers thereof and having a predetermined coefficient ofexpansion.

9. As an article of manufacture a composite wire free from pocketsbetween the layers thereof, comprising a core of nickel steel and asheath of electrolytically deposited copper.

10. As an article ofmanufacture a com posite wire free from pocketsbetween the layers thereof and having exactly a predeterminedcoefficient of expansion, comprising a core of nickel steel and a sheathof electrolytically deposited copper.

In testimony whereof, I have hereunto subscribed my name this third dayof J anuary 1921.

EMILIO ROMANELL'I.

